Piston.



H. C. MARA/50N.

FISTON.

APPLICATION FILED JULY 10,1916.

Patented Febl 11, 1919.

. s'ra s PA PISTON.

Specification of Letters Patent.

atented Feb. 11, 1919.

Application led July 10, 1916. Serial No. 108.274.

of my invention is to produce an eliiclent piston,

especially designed for use in internal combustion engines, theconstruction being such as to permit a practical elimination of slappingdue to the necessity, in piston structures rnost commonly now in use, ofproviding'suliicient clearance or looseness of fit, throughout thelength of the lpiston to compensate for expansion due pin,

to heating.

The accompanying drawings illustrate my invention. Figure 1 is an axialsectionof my improved piston; Fig. 2 an axial section. at fright anglesto the plane of Fig. 1; Fig. 3 a sideelevation in partial axial section-of a modified form; and'Fig. 4 a section on line .4-4 of Fig. 2.

,In the drawings, indicates the head, or ring-carrying portion of thepiston, provided with the usual circumferential ringrecelving grooves11, designed to receive packing ring'sof desired construction.

The head portion 10 1s comp'aratlvely short as to' that portion whichcarries the `rings and diametrically may be given sufficient clearanceto compensate for all possible increase of diameter due to heating. Thehead 10 is, however, provided with an axially-extended tubular stem, orshank, 12, of considerably less diameter than the diameter of thering-carrying portion and at its end this shank or stem is provided withan external circumferential flange 13, which is of less diameter thanthe ring-carrying portion. At diametrically opposite points, the stem 12is provided, both externally and internally, with bosses 14 which arebored to form pin-receiving openings 15 for the wrist these bosses beingpreferably arranged as near the lower end of the shank as possible, asclearly shown in the drawing.

The main guide portion or cross-head portion of the piston is formed byan accurately fitted skirt attached to the lower end of the sleeve 12 insuch manner that it is, in the main, isolated from the head section, itspoint of attachment bein so remote from that portion of the head o? thepiston which is directly affected by the heat, that there will becomparatively little conduction of' `a lower depending skirt 17, and anintermediate inwardly-projecting flange 18 mating with flange 13 andattached thereto by bolts 1 9 and nuts 20, the nuts being tightened andthen held in place -by peening the end of the bolt. The skirts 16 and 17may be made very thin and carefullymachined inside and out in order'v tobe perfectly balanced. In the form shown in Fig. 3, the upwardlyprojecting skirt section 16 is formed ofisheet metal having an inturnedflange 22 at one end and the` depending skirt section 17 is also formedof sheet metal and provided with an inturned flange 23 at one end.Flange 22 is formed to fit upon flange 13 of the head section and flange`23 is formed to rest upon flange 22, the two skirt sections being heldin place by bolts 19 and nuts` 20, as in the other construction. The twoskirt sections, having been placed in position, may be accuratelyexternally ground to fit the cylinder into which the piston is to go,and the circumferential crease 24 formed at the junction of the twoskirt sections will serve as a reservoir for lubricant. l

The upwardly extending skirt section, in either form, extends up closeto the larger portion of head 10, but is at all points separatedtherefrom, so that there can be no direct transmission of heat from thehead portion to the skirt. In order to permit the ready insertion of thewrist pin, the upwardly extending skirt 16, or 16', is perforated at 25.

During the operation, there would be an accumulation of oil in theannular space between the upwardly presented skirt 16` and the tubularstem 12, and in order to prevent too great an accumulation of oil, Islitk the lower end of the stem 12 at various points by the longitudinalslots 27 which may extend, if desired, entirely through the flange 13and up far enough to form outlets for the annular space referred to.

In practice I have found that, with the form shown in Figs. 1 and 2,most excellent results can be obtained by making the main body or headportion of the structure of aluminum and the skirt section of cast iron.In the form shown in Fig. 3, the head section may be of aluminum and theskirt sections may be of pressed steel.

In the manufacture of automobile engines at the present time, where thepiston speeds are very high. itis very essential that the pistons be notonly as light as possible, but that they be as accurately balanced aspossible and it is, therefore, important that the skirt section, orsections, be separate from the head section, not only because thenecessary stiffness of the skirt member may be obtained by the use of amaterial different from that used for the head, but' 4also because boththe head and the skirt may be carefully machined inside land out andthus proper balancing obtained. No such accuracy of balance could beobtained by a structure in which the skirts vwere integral with the mainbody. f

I claim as my' invention:

1. A piston comprisin a head section hav'- ing a tubularshank o lessdiameter than the active end and of sufficient length to re- .ceive thepitman wrist pin, a skirted cross head section formedV independently ofthe head section, said skirted cross head section comprising an upwardlyextended skirt overlying the tubular shankbut radially separatedtherefrom, and also comprising a dependingskirt, and also comprising aninwardly projecting portion formed to mate with the tubular stem, andmeans for fastening the skirted cross head to the head member at a pointdistant from theaotivev end of said hea-d member.

2. A piston structure comprisin a head member havin-g an axially extendeportion of less diameter than its active end and provided at the freeend of this extended portion with a laterally extended bolt-receivingportion; and a cross head member comprising a skirt portion formedindependently of the head member and overlying the axially extendedportion of the head member 'but separated therefrom, and also comprisingan inwardly projected portion mating with the laterally projectedportion of the head member; fastening bolts connecting said matingportions.

3. A piston comprising a head member having an axially extended portionof less diameteithan the active end and provided at the free end of thisextended-portion with an external circumferential flange; a cross headmember having an internal circumferential flange and a skirt portionoverlying the axially extended portion `of the head member but radiallyseparated therefrom, the said cross head member being formedindependently of the head member; hea-ded bolts passing through theflanges of the head member and cross head member with the heads thereofengaging the'ilange o f the head member, and nuts clamping the crosshead member upon the head member.

4. A piston comprisin a head member having an axially exten ed portionof less diameter than the active end a'nd provided at the free end ofthis extended portion with portions formed to mate with a cross headmember; a cross head member comprising a pair of oppositely arrangedsheet metal skirts each provided at one end with an inwardly extendingflange, the said inwardly extending flanges being formed -to mate witheach other and with the appropriate portion of the head member, andfastening members clamping the head member and cross head memberstogether.

5. A piston comprisin a head member having an axially exten ed portionof less diameter than the active end and provided at the free end ofthis extended portion with an extern-al circumferential flange, saidaxially extended portion having wrist pin receiving perforations betweenthe active end ferential flange, and having a skirt portion overlyingthe small extended portion of the head member and extending beyond thewrist pin perforation, said skirt member having perforations permittingthe lateral insertion of the wrist pin and bolts for clamping the crosshead member to the head member.

6. A piston structure comprisin a head member having an axially extendedportion of less diameter than its active end and provided at the freeend of said extended V portion with a lateral extension; a cross h'eadcomprising a mating pair of skirt sections each formed of sheet metaland provided flange at one end., said flanges at their mating planesforming a circumferential crease in the cross head; and means forclamping said inwardly projecting flanges together upon the lateralextension of the head member.

7. A piston structure comprisin a head member having an axially extendeportion of less diameter than its active end and provided at the freeend of this extended portion with a laterally extended bolt-receivingportion; and a cross head member comprisin g a skirt portion formedindependently of the head member and overlying the axially extendedportion of the head member but with an inwardly extendingcircumferential separated therefrom, and also comprising an externaleircmnferential ange, said axialiy extended portion having Wrist pinreceiving perforations between the active end and said circumferentialBange; perfora- 5 tions between the active end and said` eireumferentialflange; a cross head member having an' internalpeircumferential. angemating with the said external circumferential ange, and havin a skirtportion 0 overlying the small exten ed portion of the head member andextending beyond the wrist pin perforation, said skirt member havinperforations permitting the lateral` insertion of the Wrist pin; andmeans for clamping the Cross head member tothe head 15 member. i

In Witness whereof, I have hereunto set my hand at Indianapolis,Indiana, this sixth day of July A. D. one thousand nine hundred. andsixteen.,

HOWARD C. MARMON.

